Re: gEDA-user: Question for DJ about his alarm clock

[DJ Delorie <dj@xxxxxxxxxxx>]

> I figured I'd ask this in public since it might be of general interest
> to know the answer.  Also, I don't mind asking dumb questions in
> public.  I hope I am not putting you on the spot, DJ!

No problem ;-)

> I noticed that on p. 3, the ST part (U300) has PVDD and PVSS
> connections through 4.7 ohm resistors to PWR and GND, respectively.  I
> can see using a small resistor + shunt cap to GND in series with the
> power connection to attenuate power supply noise.  However, why is the
> PVSS connection to GND also going through a resistor?

There's noise on both power and ground lines.  The P* pins are for the
PLL's power supply, which need as clean a power source as you can
provide.

> I guess I could look at the part's datasheet, but the resolution of
> the PNG file isn't good enough for me to resolve the part no.  (Or
> maybe my computer's screen doesn't offer enough resolution.....)

Click on the text link, which links to the *.sch directly.

The mp3 chip is an STA013 dsp chip.


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